To provide a vehicle such as an automobile and a tire which allow comfort wheel steering, automobile makers and tire makers in these days have investigated the wheel steering comfort of a vehicle and performed the development of vehicles and tires by using various methods.
In the development of vehicles and tires, when it is evaluated whether or not the steering of a wheel is comfort, the evaluation is generally performed in most cases by using subjective Judgment by a driver or quantitatively measuring the behavior of a vehicle by providing the vehicle with a measurement sensor for an acceleration rate or the like and acquiring physical measurement data representing the behavior of the vehicle.
To evaluate the degree of load placed by a given work activity while it is performed, it has also been performed in these days to acquire an electromyogram representing the waveform of a myoelectric potential from an activity worker and thereby quantitatively recognize the load on the muscle of the activity worker. It is considered that the myoelectric potential enables proper evaluation of the degree of load placed by a given work activity while it is performed since the myoelectric potential can be measured easily and conveniently and is also high in responsivity. It can also be considered to apply a method of evaluating a degree of load placed by a work activity which uses the electromyogram to the steering of a vehicle wheel by a driver.
However, since the steering of the vehicle wheel by the driver is a work activity which is performed antagonistically by deltoid muscles which are a pair of left and right muscles provided in a human body in bilaterally symmetrical relation, the fact is that the one of the muscles on which less load is placed does not correspond to a higher degree of comfort during wheel steering.
For example, when a force for wheel steering is small, the load on the muscles of the drive is reduced but the problem is encountered that the steering wheel should be held incessantly with the small force. When the force for wheel steering is large, the load on the muscles when the driver steers the wheel is increased but the necessity to constantly hold the steering wheel is reduced because the wheel is stable.
Accordingly, the degree of comfort of wheel steering cannot be evaluated properly from an index of load on a muscle obtained through the measurement of an electromyogram.
There is also a method which measures the fluctuations of the electroencephalogram, the fluctuations of the heart rate, the blood pressure, and the like as the bio-information of the driver. In either case, however, it is necessary to give a specified restriction to the driver, such as the retention of constant breathing, so a problem of placing extra burden on the driver is encountered. In addition, such bio-information has a problem in that it requires a sufficiently long measurement period in terms of analysis performed as a post process and a result which is high in responsivity cannot be obtained. Accordingly, the degree of comfort of actual wheel steering cannot be evaluated properly.
Such problems are not limited to the steering of a vehicle wheel and similarly occur in the case where the degree of work comfort is evaluated when a pair of left and right muscles provided in a human body in bilaterally symmetrical relation antagonistically perform a work activity.
In view of the foregoing, it is therefore an object of the present invention to provide an apparatus for evaluating a degree of work comfort by measuring a myogenic action during a work activity which is performed antagonistically by a pair of left and right muscles provided in a human body in bilaterally symmetrical configuration and provide an apparatus and method of evaluating a degree of work comfort which allow the evaluation of the degree of comfort of a work activity from the result of short-period measurement without imposing a restriction on an activity worker.